2009 Academic Challenge

Transcription

1 009 Acadeic Challenge PHYSICS TEST - REGIONAL This Test Consists of 5 Questions Physics Test Production Tea Len Stor, Eastern Illinois University Author/Tea Leader Doug Brandt, Eastern Illinois University Author Kevin Pitts, University of Illinois at Urbana-Chapaign Reviewer Mary Weaver, WYSE Coordinator of Test Production GENERAL DIRECTIONS Please read the following instructions carefully. This is a tied test; any instructions fro the test supervisor should be followed proptly. The test supervisor will give instructions for filling in any necessary inforation on the answer sheet. Most Acadeic Challenge sites will ask you to indicate your answer to each question by arking an oval that corresponds to the correct answer for that question. Only one oval should be arked to answer each question. Multiple ovals will autoatically be graded as an incorrect answer. If you wish to change an answer, erase your first ark copletely before arking your new choice. You are advised to use your tie effectively and to work as rapidly as you can without losing accuracy. Do not waste your tie on questions that see too difficult for you. Go on to the other questions, and then coe back to the difficult ones later if tie reains. *** TIME: 40 MINUTES *** DO NOT OPEN TEST BOOKLET UNTIL YOU ARE TOLD TO DO SO! 009 Worldwide Youth in Science and Engineering WYSE, Worldwide Youth in Science and Engineering and the WYSE Design are service arks of and this work is the Copyright 009 of the Board of Trustees of the University of Illinois at Urbana - Chapaign. All rights reserved.

2 Fundaental Constants Quantity Sybol Value Avogadro s nuber N A /ol Boltzann s constant k J/K Electron charge agnitude e C Pereability of free space μ 0 4π 10 7 T /A Perittivity of free space ε C /(N ) Planck s constant h J s Electron ass e kg Neutron ass n kg Proton ass p kg Speed of light in vacuu c /s Universal gravitational constant G N /kg Universal gas constant R J/(ol K) Other inforation: Acceleration of gravity at earth's surface g = 9.80 /s 009 Regional

3 WYSE Acadeic Challenge Physics Test (Regional) A bullet is fired horizontally near the surface of the earth with a uzzle speed of 45 /sec. Assuing air friction to be negligible, what is the agnitude of the vertical displaceent of the bullet before it strikes a target that is at a horizontal distance of 1 away? a. 1.5 b..49 c d. 0.6 e The otion of an object along the x-axis is described by the equation: x = ( 70.0 ) + ( /s) t ( 4.0 /s ) t. What is the acceleration of the object at t =.0 s? a. b. c. d. e. 8.0 /s 4.0 /s.0 /s 16.0 /s.0 /s. For the sae situation as in proble, what is the average velocity of the object between t = 0.00 s and t = 0.50 s? a. 15 /s b. 0. /s c. 110 /s d. 50 /s e. /s 4. The length of tie an average force of 40.0 N toward the south ust act on an object so that a 00. kg object changes its oentu fro 00. kg /s north to 100. kg /s south is a s b s c. 0.0 s d. 000 s e s 009 Regional

4 Physics 5. A 58.0 kg driver accelerates a 1500 kg car fro 4.00 /s to 0.0 /s along a horizontal stretch of road. How uch work has the car done on the driver during this tie interval? a J b J c J d J e. none 6. In the situation in proble 5, the car travels a distance of 15 as its speed changes fro 4.00 /s to 0.0 /s. If the acceleration is assued to be constant, what is the agnitude of the acceleration of the car? a /s b..08 /s c /s d /s e /s 7. The change in oentu of a syste is a. always zero. b. equal to the work done on the syste. c. equal to the net force acting on the syste. d. equal to the total ipulse acting on the syste. e. equal to the acceleration of the center of ass of the syste. 8. The universal law of gravitation is credited to a. Kelvin. b. Newton. c. Einstein. d. Thoson. e. Boyle. 9. According to the universal law of gravitation, the agnitude of the gravitational force between two point asses is a. proportional to the product of their asses, and inversely proportional to their separation distance. b. proportional to the product of their asses, and inversely proportional to the square of their separation distance. c. proportional to the su of their asses, and inversely proportional to their separation distance. d. proportional to the su of their asses, and inversely proportional to the square of their separation distance. e. none of the above. 009 Regional

5 Physics 10. An appropriate unit of easure for pressure is a. Bernoulli. b. Newton per eter. c. Pound inch. d. Pascal. e. Luen. 11. According to the special theory of relativity, an observer would observe that a. a clock oving toward the observer runs too fast. b. a clock oving away fro the observer runs too fast. c. any clock oving relative to the observer runs norally. d. any clock oving relative to the observer runs too fast. e. any clock oving relative to the observer runs too slowly. 1. Two identical pucks, sliding on a horizontal, frictionless surface, collide with each other, and thus ove off in new directions. As a result of the collision, it is observed that the pucks have been peranently dented. Coparing before collision to after collision, which of the following ust be true for the two puck syste? a. The kinetic energy and oentu of the syste will both be conserved. b. Neither kinetic energy nor oentu of the syste will be conserved. c. The oentu of the syste will be conserved, but the kinetic energy of the syste will be less after the collision. d. The oentu of the syste will be conserved, but the kinetic energy of the syste will be greater after the collision. e. The kinetic energy of the syste will be conserved, but its oentu will be less after the collision. 1. Object A has twice the aount of oentu of object B, but half the kinetic energy of B. Assuing that these two objects are oving with speeds uch less than the speed of light, which of the following ust be true? a. It is not possible for A to have twice the oentu and half the kinetic energy of B. b. The ass of A would have to be eight ties the ass of B. c. The ass of A would have to be four ties the ass of B. d. The ass of A would have to be two ties the ass of B. e. B would have to have a larger ass than A. 14. A 150. g, unifor eter stick is in static equilibriu when a frictionless fulcru is placed at the 50.0 c ark on the eter stick. Leaving the fulcru at this position, a 5.0 g weight holder is placed at the 10.0 c position, and is loaded with 100. g. If static equilibriu is to be aintained, how uch ass ust be added to a second, identical weight holder which is located at the 75.0 c position on the eter stick? a. 00. g b g c g d g e. 175 g 009 Regional

6 Physics For the situation described in proble 14, the second weight holder is instead loaded with 50. g and oved along the eter stick until static equilibriu is achieved. (The position of the fulcru and the first holder s position and load reain the sae as before.) What agnitude of force ust the fulcru exert on the eter stick? a. 5.9 N b N c..9 N d N e..4 N 16. A ass of 54 gras has an acceleration of 500. illieters per second per second. What is the net agnitude of force expressed in Newtons acting on the ass? a N b. 889 N c N d. 1.8 N e N 17. Variables T and R are plotted as shown below, resulting in a straight line. The shown rise, run, and intercept values are in the units shown on the graph. What is the equation that relates T and R? a. b. c. d. e. s T = 0.05 R s R = 0.0 T s s T s = 0.05 R s T = 0.05 R s s T = 0.05 R s T,(s ) Period Squared vs. Radius Cubed (0,0) R,( ) 18. A cart with a spring-fired cannon oves fro left to right with a constant speed of 1.00 /s. At position X the cannon launches a arble upward with respect to the cannon by forcing the arble through the vertical barrel of the cannon. The uzzle speed of the arble is.00 /s. According to a person standing beside the cart in the lab, which path would the arble ost closely take? a. path A b. path B c. path C (vertically upward, then downward) d. path D e. path E A B C X D E 009 Regional

7 Physics A 1.50 kg bob, attached to the lower end of a vertically oriented, assless spring of spring constant 170. N/, is undergoing siple haronic otion as it oves up and down. In a certain coordinate syste with up defined as positive, the spring-ass syste has the following initial conditions: the bob has a vertical position equal to 0.00 ; the spring is 0.00 longer than its no load length; and the bob is oving downward with a speed of.40 /s. How fast will the bob be oving when its coordinate position is 0.400? a /s b..50 /s c..78 /s d. 1.7 /s e. 1.4 /s 0. Given force F 1 = 80.0 N in the direction 155 o. What force ust be subtracted fro F 1 to obtain the result.8 N in the direction 90.0 o? a. 7.5 N in the direction 180 o b. 46. N in the direction 65.0 o c N in the direction 11 o d. 46. N in the direction 45 o e. none of the above 1. A spool sitting upon a horizontal table surface is acted upon by the two forces shown, plus a noral force fro the table s surface, and a frictional force which prevents the spool fro slipping. With respect to point P, how uch torque is produced by the two given forces? a. rf b. rf c. 5 rf d. 7 rf e. 11 rf F r r r F P. A assless, rigid rod is pinned at point P so that it ay freely rotate but ay not translate. Two point objects, each of ass, are affixed to the ends of the rod, as shown. The rod is initially at rest when another point object of ass, oving with an initial speed v, strikes and sticks to the rod at the position shown. What is the angular speed of the rod after the collision? a. v / (5r) b. v / (8r) c. v / (9r) d. v / (11r) e. v / r v P r r r 009 Regional

8 Physics 6. In the preceding situation, which physical quantities are conserved in the syste of point asses and rod? a. Kinetic energy, linear oentu, and angular oentu are all conserved. b. Kinetic energy and linear oentu are both conserved. c. Kinetic energy and angular oentu are both conserved. d. Linear oentu and angular oentu are both conserved. e. Angular oentu is conserved, but not kinetic energy nor linear oentu. 4. Dots f and j in the diagra below indicate the extree positions of an object oving with siple haronic otion under the action of a spring. Dot h represents the equilibriu position. The distance between adjacent dots is 5.00 c, and the period of the oscillation is 48.0 seconds. When the object is oving to the right, how long does it take for the object to ove fro f to g? a. 1.0 s b s c s d s e s f g h i j 5. Using the sae spring and object as in proble 4, if the aplitude of the oscillation is doubled, what will the resulting period of oscillation be? a s b s c s d. 19 s e. 4.0 s 6. In the diagra shown below, a block of ass 1.50 kg is connected to a block of ass by a light, inextensible string which passes over a pulley that has a oent of inertia equal to kg and a radius of 8.00 c. Assuing that the string does not slip on the pulley and that the pulley has negligible axle friction, what is the string tension difference, T 1 T, if the 1.50 kg ass has a downward acceleration of 6.00 c/s? a N b N c N d N e N T T kg 009 Regional

9 7. A 6.00 kg ass and a 4.00 kg ass are connected by a light, inextensible string that passes over a frictionless pulley of negligible ass, as shown below. Let T be the tension in the pulley s supporting string. When the syste is operated on planet X, the 6.00 kg ass is observed to have an acceleration of agnitude 1.60 /s. What is the acceleration due to gravity on this planet? Physics 7 T Stationary support a /s b /s c /s d..0 /s e /s 4.00 kg 6.00 kg 8. For the sae situation as in proble 7, in ters of the acceleration due to gravity, g x, on planet X, what is the tension, T, in the upper, assless string? a..00 kg gx b kg gx c kg gx 9.60 N d kg gx N e kg gx N 9. A boat travels with a speed of 8.50 k/h relative to the water in a river which flows at a velocity of 5.00 k/h due east. What should the heading of the boat be in order that it travel due south? a. due south b. 0.5 o west of south c. 6.0 o west of south d o west of south e o west of south 0. In a vacuu tube located in a laboratory on earth, a unifor agnetic field of strength B points in the direction due east. A positive charge oves through the vacuu tube under the influence of the agnetic field and the earth s gravitational field. If the charge is oving at the proper speed, the net force on the charge will be zero if the charge oves a. due north. b. due east. c. due south. d. straight up. e. straight down. 009 Regional

10 A B 4.00 kω Physics 8 1. If 5.00 A of current flows through the 4.00 kω resistor, what is the potential difference across the.00 kω resistor? 1.00 kω.00 kω a. 0.0 V b. 1.0 V c V d V e V..00 oles of an ideal gas are heated slowly so that the gas goes fro an initial pressure and volue (.00P 0,.00V 0 ) to a final pressure and volue (8.00P 0, 8.00V 0 ) such that during the process the pressure of the gas is directly proportional to the volue of the gas. How uch work is done by the gas during this process?.00 kω a. 0.0 P 0 V 0 b P 0 V 0 c. 1.5 P 0 V 0 d. 5.0 P 0 V 0 e. 7.5 P 0 V 0. For the sae situation and process as in proble, if the teperature of the gas in the initial state is T i, what is the teperature of the gas when its volue is 5 V 0? a T i b..78 T i c T i d T i e T i 4. A single loop circuit consists of a 9.00 V source, a 1.50 kω resistor, a.00 F (copletely discharged) capacitor, and a switch. When the switch is closed, the capacitor begins to charge. What is the rate of voltage change across the capacitor at the instant the potential difference across the capacitor is 4.00 V? a V/s b..00 V/s c. 1. V/s d V/s e V/s 5. The following standing wave is set up in a pipe open at one end and closed at the other. In the diagra, A = displaceent antinode and N = displaceent node. If V is the speed of sound in air and L is the effective length of the pipe, what is the frequency of sound indicated by the standing wave shown? a. 1.5 V/L b..50 V/L c V/L d V/L e V/L A N A N A N 009 Regional